The invention relates to a wiper system for front windshields of motor vehicles.
Wiper systems serve to maintain a free view in the event of a spontaneously occurring action upon vehicle windshields with sight-obstructing substances, in particular in the event of precipitation-induced sight obstructions due to adverse weather conditions.
Front windshields with enhanced functionality are increasingly found in modern motor vehicles. That is to say, in addition to ensuring that the driver has an unobstructed view, modern front windshields have to satisfy further functions relevant to safety, from mechanical occupant protection to static incorporation in strength calculations of bodywork and passenger compartment. This leads, firstly, to changes in the front windshield geometry and size and, secondly, to changes in the front windshield material in order to be able to satisfy the increased safety and strength requirements.
As a result of novel front windshield concepts, sometimes increased demands are made of wiper systems to be used. An enlarged field of view changes the viewing habits of the driver. Without any doubt, safety is served if said changed viewing habits are kept to even in adverse weather conditions, i.e. if the front windshield can be cleaned as completely as possible by the wiper system, that is to say, the wiper blades have to be guided under uniform contact pressure over the maximum possible surface regions.
A movement of the wiper blade is frequently realized by means of a pivotable arm which is connected via an articulation part to a fastening part which is pivoted about a fixed axis. The fastening part is driven via a wiper linkage which is generally installed such that it is concealed and, in conjunction with a wiper motor, transmits an alternating linear movement to a lever connected to the fastening part, or to a correspondingly designed bearing part. A pivotable fixing of the fastening part ensures an alternating pivoting movement of the fastening part, which movement is transmitted to the wiper arm. An elastic wiper blade is fitted at the end of the pivotable wiper arm. So that the wiper blade can follow the curved surface of the front windshield, the articulation part is usually designed in such a manner that the pivotable arm is connected to the fastening part in a manner such that it can be deflected perpendicular to the pivoting plane of the fastening part, and is prestressed in the direction of the front windshield by spring force, thus producing the required contact pressure at the wiper blade.
In order for the wiper blade to be able to traverse the maximum possible surface region of the front windshield, it is frequently endeavored to place the pivot axis as close as possible to or into the front windshield. This requirement sometimes also results from the installation spaces which are available in the vehicle body and make it appear expedient to place the wiper drive under the front windshield.
It is therefore known to guide a bearing shaft, which determines the pivot axis of the wiper system and to which a fastening part supporting the wiper arm is fitted, through an opening in the front windshield. However, this solution has the disadvantage that a piercing, which is required for this, of the front windshield is no longer permissible in many modern glass materials used for front windshields. Such a measure, which has an adverse effect on the surface stability and the fracturing behavior, is impermissible in particular in the case of frequently used laminated glass.